1. Field of the Invention
The present invention relates to a high-zoom-ratio zoom lens, an optical apparatus using the zoom lens, and a method for varying the focal length of the zoom lens.
2. Related Background Art
There have been proposed high-zoom-ratio zoom lenses suitable for an electronic still camera and the like (for example, Japanese Patent Application Laid Open No. 2005-257868).
In a conventional high-zoom-ratio zoom lens, since a first lens group and a third lens group are fixed with respect to an image plane upon varying a state of the focal length from a wide-angle end state to a telephoto end state, refractive power of a second lens group is necessary to be strong, so that variation in longitudinal chromatic aberration becomes large.